Device for separating paper sections from a paper web wound onto a paper roll, as well as a knife for separating the paper sections

ABSTRACT

The invention relates to a device for separating paper sections (74) from a paper web wound onto a paper roll and for allowing easy manual access to the paper web that follows after the separated paper section, whereby the device comprises a cutting cylinder (40), which extends over at least the paper width, and a knife (42) that extends essentially over the entire roller width, whereby the knife (42) comprises a blade (114) and a series of teeth (120, 122, 124, 126), which are arranged spaced apart along the length of the blade, whereby the groups of teeth (120, 122, 124, 126) are separated from each other by cut-outs (128, 130, 132), and whereby the cutting roller (40) is associated with a pressure roller (44), which has a slit-shaped opening (46) and is coupled to the cutting roller (40). In order to be able to cut and dispense paper webs of high strength and elasticity reliably and trouble-free, it is intended that each of the cut-outs (128, 130, 132) comprises two cutting edges (162, 164, 166, 168), which extend parallel to each other and transversely to the longitudinal extent of the knife (42), that at least one of the cutting edges (162, 164, 166, 168) is a cutting edge of a group of teeth adjoining the cut-out, and that the cutting roller (40) comprises along its circumferential surface (134) circumferential grooves (128, 130, 132), each of which corresponds to one of the cut-outs.

This application claims priority to German patent application number 102017 110 516.6, filed May 15, 2017, the contents of which areincorporated herein by reference.

The invention relates to a device for separating paper sections from apaper web wound onto a paper roll in accordance with thepre-characterizing clause of claim 1 as well as to a knife forseparating the paper sections in accordance with the pre-characterizingclause of claim 7.

A device for separating paper sections as well as a knife for a deviceof that type is known from DE 20 03 354 A. This prior-art devicecomprises a perforating device for dividing the paper band intoindividual sheets that contains a rotatable knife with a perforatingcutting edge and—rotating synchronously with the latter—with a slottedroller that is equipped with a slit that serves to accept the radiallyouter part of the knife. The cutting edge of the knife is embodied witha sawtooth shape. Additionally, the knife comprises a plurality ofgrooves, into which engage the ridges of a counterpart when the knife ismoving into the immediate vicinity of the slotted roller and is movingpast it in a rotating manner. The knife passes the slotted roller in arotating manner, so that the radially outer part of the knife engagesinto the slit and the knife's cutting edge perforates the entire widthof the paper web, with the exception of those parts of the paper webthat are situated opposite the grooves. The unperforated portions of theweb possess sufficient tensile force to allow the user to pull the paperweb from the dispenser using a gentle steady pulling force.

US 2005/0224860 A1 relates to a paper dispenser, which comprises ahousing with a cover, a cylinder drum, a cutter device integrated in thecylinder drum, as well as an energy storage mechanism. The cutter devicecomprises two knifes that are arranged spaced some distance apart. Thedistance between the knifes can be adjusted via an eccentric elementsituated in a region between the knifes so that it becomes possible todeliver sections of different sizes during the dispensing of a paperweb. Consequently, it is possible to use paper webs with differenttensile strengths in the same dispenser.

DE 28 14 792 A1 relates to a device for issuing paper sections of apredetermined length and comprises a device for separating the papersection from the paper web wound onto a paper roll and for allowing easyaccess to the paper web following the dispensing of the separated papersection, whereby the device is operated by pulling on a paper end. Thedevice consists of at least one cutting roller, which has a width thatcorresponds to at least the width of the paper web, and which features acutting line that at least partially encloses an angle α—different fromzero—with the generatrix of the cutting roller. The cutting rollercomprises a fixed knife, which substantially extends over the entirewidth of the roller and protrudes from the roller shell. Associated withthe cutting roller is a pressure roller, which has a slit-shaped openingthat matches the knife arrangement. The two rollers are coupled to eachother by means of geared wheels, which possess a partial circle diameterthat corresponds to the roller diameters, and which effect a synchronousmovement of the roller in such a way that the paper web—stretchedtightly across the slit-shaped opening—is perforated by a knife, wherebyduring the course of this cutting process the knife penetrates into theslit-shaped opening.

The knife comprises a cutting edge that is embodied sawblade-like.According to this prior art, a cutting line of the knife forms an angleα with the generatrix of the cutting roller, whereby the anglecorresponds to the constant angle of inclination of the helical line.Pulling the end of the paper web results in a rotation of the cuttingroller by way of frictional contact. The knife engaging the paper web,which has been stretched tight with the help of the deflection roll,marks the start of the separation process of the paper section from thesubsequent paper web. This separating process is not completed beforethe end of the knife engages with the paper web and a sufficiently largepiece of the following paper web protrudes from the dispenser and iseasily accessible by hand for the subsequent paper dispensing process.

EP 1 153 565 A1 relates to a mechanism for cutting and providingsections of a tape material, in particular paper towels, comprising atleast one cylinder, which in a support structure is free to rotate aboutone axis and drags along an end section of at least one web, wherebyarranged in the cylinder is/are one or several movable knife/s, whichmay protrude from the cylinder for cutting the end section of the paperweb, whereby the knifes are connected to a shaft that is free to rotateabout one axis, e.g. oriented parallel to the longitudinal axis of thecylinder. The shaft comprises at least one first means, which protrudesfrom one side of the cylinder and is free to rotate about an angularportion of a circumference. The rotational movement is effected by atleast one second means, which shifts along a direction parallel to thelongitudinal axis of the movable knife and rotates about the axis,whereby the rotation-translation movement of this second means issynchronized to the rotational movement of the cylinder. The rotationalmovement of the cylinder is initially started by pulling on the paperweb for a distance equivalent to half a rotation, whereby subsequentlythe second half rotation is caused by a tension spring, which isconnected between a side wall and a geared wheel that is connected tothe axle of the cylinder. A knife with a sawtooth geometry is used forcutting the paper.

DE 36 90 545 T1 relates to a dispenser for rolls of flexible tapematerial, comprising a feed roll and a cutter blade. The cutter bladeconsists of a series of teeth, which are arranged some distance fromeach other along the length of the blade. In this prior art, four pairsof teeth are present along the length of the blade, whereby these pairsof teeth are separated by cut-outs. Employing this shape of cutting edgeallows the cutting action that is performed on the web of the flexibleband material when it is supplied via the feed roll to result in astraight cut that extends in parallel to the axis of the feed roll, butthis leaves three small sections of the web uncut, which correspond tothe width of the sections and to the length of the sections still on thecircumferential surface of the feeder roll.

By leaving these small uncut sections of the web, which across the widthof the web contain a section between each other, serves to maintain thecontinuity of the web, when the web has essentially already been cut butstill remains within the confines of the dispenser chassis beforereaching the dispensing outlet. When the web is pulled further out ofthe dispenser housing by the future user of the now determined sheetlength, the future user applies a low level of pulling force, which veryeasily separates the spaced-apart uncut sections, which are formed bythe configuration of the cutting blade and the spacing between the slitsarranged in the circumferential surface of the feed roll.

Starting from this basis, the objective of the present invention is tofurther develop a device of the type mentioned above in a way so thatpaper webs of high strength and elasticity can be cut and dispensed in areliable and trouble-free manner.

Another objective of the invention is to further develop a cutting knifeof the above-mentioned type in a way so that paper webs of varyingstrength and elasticity, in particular paper webs of high strength andelasticity, can be cut in a reliable and trouble-free manner.

This objective is met by the invention for example with the features ofclaim 1.

Each of the cut-outs comprises two cutting edges, which extend inparallel to each other and extend transversely to the longitudinalextent of the knife, whereby at least one of the cutting edges is acutting edge of a group of teeth bordering the cut-out. A maximum lengthof the cutting edges is achieved by embodying the cutting edges of thegroup of teeth bordering the cut-outs in parallel or substantially inparallel.

Along its circumferential surface, the cutting roller comprisescircumferential grooves, each of which corresponds to one of thecut-outs. The width and the depth of the groove preferably correspond tothe width and the depth of the cut-out.

In an especially preferred embodiment, it is intended that theslit-shaped opening of the pressure roller comprises bridges extendingalong the circumferential direction, whereby a width and a spacing ofthe bridges corresponds to the width and a spacing of the cut-outs inthe knife, so that during a relative movement between the cutting rollerand the pressure roller, the bridges engage into the cut-outs of theknife and work together with the adjoining cutting edges in ascissor-like manner. This achieves a clean cut in the area of thebridges, which in turn leads to a smooth and trouble-free continuedtransport of the paper section and simplifies tearing-off the papersection.

Further it is intended in a preferred embodiment that the knifecomprises a knife edge that protrudes from the cutting roller and formsan angled section. This ensures that during a relative movement betweenthe cutting roller and the pressure roller, at the moment when the knifeedge penetrates into the paper web stretched along the circumferentialsurface of the pressure roller, the entry angle will be set to anoptimum value.

The angled section preferably comprises the groups of teeth and isangled relative to the blade along a deflection line with an angle αwith 15°≤α≤50°, preferably α=35°.

It is further intended that the cutting roller comprises two sectionswith a preferably semi-circular cross-section, and that the blade of theknife is fixed in position, e.g. clamped, between the semi-circularsections. This embodiment facilitates both a simple assembly and anuncomplicated exchange of the knife.

To achieve an optimum scissor action between the transversely extendingcutting edges of the knife and the radial bridges of the pressureroller, it is intended that the spacing between the bridges of thepressure roller corresponds to the width of a group of teeth of theknife edge.

The invention further relates to a knife for a device for separatingpaper sections from a paper web wound onto a paper roll, whereby theknife comprises a knife blade with teeth and/or groups of teeth, whichare arranged spaced apart along the length of the knife blade, wherebythe teeth and/or groups of teeth are separated from each other bycut-outs. The cut-outs have two cutting edges that extend in parallel toeach other and transversely to the longitudinal extent of the knife,whereby at least one of the cutting edges is a cutting edge of a toothor group of teeth bordering the cut-out.

The invention intends that the cutting edges of the groups of teethpossess flanks that rise in the direction toward the cut-outs, whichfacilitates a maximum length of the cutting edges. Flanks that rise inthe direction of the cut-out serve to achieve an acute angle, whichimproves the knife's cut into the paper web.

The teeth or groups of teeth are angled with respect to the blade alonga deflection line by an angle α with a 15°≤α≤55°, preferably α=35°.

The teeth or groups of teeth include outer teeth that adjoin the lateraledge of the blade as well as at least two inner groups of teeth, wherebya cutting edge of the inner group of teeth is embodied with a W-shapedgeometry and whereby a cutting edge of the outer group of teeth isembodied with a triangular geometry.

It is further intended that the cutting edges of the inner groups ofteeth, which border the cut-outs, extend in parallel to each other.

Further details, advantages, and features of the invention are not onlyfound in the claims, the characteristic features listedtherein—individually and/or in combination—but also in the followingdescription of the figures.

The figures show:

FIG. 1 shows a front view of a device for dispensing paper sections of apredetermined length without the covering hood,

FIG. 2 shows in a sectional view the device of FIG. 1 along a sectionline A-A, with paper roller, cutting roller, and pressure roller,

FIG. 3 shows a lateral view of the device of FIG. 1, from the left, withgearwheel transmission and return spring,

FIG. 4a ) shows a lateral view of the gearwheel transmission with returnspring of FIG. 3 in its neutral position,

FIG. 4b ) shows in a sectional view the roller arrangement in itsneutral position,

FIG. 5a ) shows a lateral view of the gearwheel transmission in theknife-entry position,

FIG. 5b ) shows in a sectional view the roller arrangement in theknife-entry position,

FIG. 6a ) shows a lateral view of the gearwheel transmission in theengaged-knife position,

FIG. 6b ) shows in a sectional view the roller arrangement in theengaged-knife position,

FIG. 7a ) shows a lateral view of the gearwheel transmission in theknife-withdrawal position,

FIG. 7b ) shows in a sectional view the roller arrangement in theknife-withdrawal position,

FIG. 8 shows a lateral view of the device of FIG. 1; seen from theright, with hand wheel,

FIG. 9 shows a perspective representation of a pressure roller,

FIG. 10 show a perspective representation of the cutting roller withknife,

FIG. 11a ) shows a top view onto the knife, and

FIG. 11b ) shows a lateral view of the knife.

FIG. 1 shows a front view of a device 10, referred to as a paperdispenser hereinafter, for dispensing paper sections of a predeterminedlength. The device comprises a housing 12 with a rear wall 14 to bemounted to a wall (not illustrated), as well as a covering hood 16. Fromthe rear wall 14 extend holding elements 18, 20 for accommodating apaper roll 22. From the paper roll 22 issues a paper web 24, which isaccommodated in a device 26 for separating and dispensing papersections. The device 26 comprises a right-side wall 28 as well as aleft-side wall 30, which are connected to the rear wall 14. The sidewalls 28, 30 are connected on the front side via a brace 32. From thebrace 32 extends along the vertical direction a pressure spring 34,which is in contact with a surface 36 of the paper web 24 or the paperroll 22 and prevents creasing of the paper web 24. The pressure springis pivotably mounted around a hinge 38 and can be pivoted laterally tothe right or the left to facilitate exchanging the paper roll 22. Thelength of the pressure spring is such, that the pressure spring 34 inits laterally pivoted position prevents the covering hood 16 fromclosing.

FIG. 2 shows a sectional view of the paper dispenser 10 along thesection line A-A. The device 26 comprises a cutting roller 40 with afixed knife 42 that extends along the longitudinal axis of the cuttingroller as well a pressure roller 44 with a slit-shaped opening 46, whichextends along the longitudinal direction of the pressure roller 44, andinto which the knife 42 can engage during a synchronous movement of therollers 40, 44. Each of the rollers 40, 44 is supported in the sidewalls 28, 30 by shaft journals 48, 50. At their ends, each of the shaftjournals 48, 50 features geared wheels 52, 54 or 56, 58, which serve tocouple the rollers 40, 44.

Deflecting rollers 60, 62 are provided for guiding the paper web, eachof which is supported on an axle 64, 66, which extend between the sidewalls 28, 30.

The paper web 24 is deflected by the deflecting rolls 60, 62 and isguided along a circumferential section 72 around the pressure roller 44by circumferential guide elements 68, 70. One end 74 of the paper web 24is guided through a withdrawal opening 76 in the covering hood 16 andmay be grasped by a user. To ensure that the end of the paper web 74 isguided into the withdrawal opening 76, a guide element is provided inthe area of the withdrawal opening 76 and extends along the pressureroller 44 between the side walls 28, 30.

The guide elements 68, 70 are connected in the area of the cuttingroller 40 by guide lands 71 that extend in the circumferential directionand are arranged spaced apart. The guide lands 71 serve to guide thepaper web 30 in the region of the guide elements 68, 70, where the knife42 engages into the opening 46 of the pressure roller 44.

FIG. 3 shows a lateral view of the paper dispenser 10 and illustratesthe geared wheel 52 of the cutting roller that is connected to the shaftjournal 48, as well as the geared wheel 56 of the pressure roller 44that is connected to the shaft journal 50. The geared wheels 52, 56 forma gear unit with a 1:1 transmission ratio and effect a synchronousmotion of the rollers in such a way that the paper web 24, which hasbeen stretched tightly along the circumferential surface 72 of thepressure roller 44, is cut or pierced by the knife 42 when the paper end74 is being pulled, whereby during this cutting operation the knife 42penetrates into the slit-like opening 46.

The geared wheel 52 is coupled to the lateral wall 30 via a tensionspring 80 in a way so that a pulling movement acting on the paper end 74in the direction of the arrow 82 in accordance with FIG. 2, effects arotation of the pressure roller 44 in the direction of the arrow 84, onaccount of a frictional engagement between the paper web 24 and thecircumferential surface of the pressure roller. Due to the coupling ofthe geared wheels, the geared wheel 48 is moved in the direction of thearrow 86, which results in a tensioning of the tension spring 80. Afterhalf a rotation of the pressure roller 44, the tension spring hasreached its maximum tension, so that during continued pulling of thepaper end 74 the tension spring 80 contracts, which effects an automaticfurther conveyance, which in turn guides a new paper end from theopening 76.

FIGS. 4 to 7 show individual positions of the cutting roller 40 relativeto the pressure roller 44 when a pulling motion acts on the paper end74.

FIGS. 4a ) and 4 b) show the geared wheels 48, 50 and the rollers 40, 44in a neutral position, in which the tension spring 80 is relaxed. Inthis, an effective line 88 of the tension spring 80 extendssubstantially perpendicular to a line 90 that connects the shaft ends48, 50. The paper web 24 is in contact with the pressure roller 44 alongits circumferential surface and is pulled tight in the area of theslit-shaped opening 46.

FIGS. 5a ) and 5 b) show the geared wheels 48, 50 as well as the rollers40, 44 in a knife-engaging position, e.g. after a rotation ofapproximately 25°, whereby the knife 42 penetrates the paper web andenters into the slit-shaped opening 46, which starts the separationprocess. In this position, the knife 42 comes into contact with thepaper web. Pulling the paper end 74 even further results in an at lastsectional separation (perforation) of the paper section by thepenetration of the knife 42 into the slit-like opening 46.

FIGS. 6a ) and 6 b) show the geared wheels 46, 50 and the rollers 40, 44in the engaged-knife position, in which the knife 42 is completelyaccommodated in the slit-like opening 46.

Pulling the paper end 74 results in the tension spring 80 being furthertensioned, whereby pursuant to FIG. 7a ) and FIG. 7b ) the knife42—after a rotation of approximately 120°—is no longer engaged in theslit-like opening 46 (knife withdrawal position).

Pulling the paper end 74 serves to further tension the tension spring80, until the rollers 40, 44 have completed half a rotation. After theeffective line 88 of the tension spring 80 has crossed the centre of thegeared wheel, the contraction of the tension spring 80 results in anautomatic further conveyance of the paper web 24, together with theseparated paper section. Subsequently, the paper section 74 can beseparated from the paper web 24 along the perforated cutting line.

FIG. 8 shows a lateral view of the paper dispenser 10 from the rightside and shows the geared wheels 54 and 58, which are in an engagedposition. A hand wheel 92 is coupled to the geared wheel 58 for thepressure roller 44. The hand wheel 92 facilitates a manual operation ofthe pressure roller 44 for threading the paper web 24, e.g. after thepaper roll 22 has been exchanged.

The geared wheel 58 of the pressure roller 44 interacts with a lockinglever 94, which is pivotably mounted on a rod 96. The locking leverlocks the geared wheel 58 along the direction of the arrow 94.

FIG. 9 shows a perspective representation of the pressure roller 44 withthe shaft 50 and the slit-shaped opening 46. The slit-shaped opening 46extends along the longitudinal direction of the pressure roller 44 allalong the latter's longitudinal extent. The slit-shaped opening 46comprises four sections 98, 100, 102, 104, which are separated bybridges 106, 108, 110 extending in the radial and the circumferentialdirection.

FIG. 10 shows a perspective representation of the cutting roller 40 withthe fixed knife 42. The knife 42 comprises a knife edge 112 as well as aknife blade 114, which is accommodated in the cutting roller 40. In theillustrated embodiment example, the cutting roller 40 comprises twoelements 116, 118, which possess a semi-circular cross-section, and inbetween which the knife blade 114 is clamped.

The knife edge 112 comprises four sections 120, 122, 124, 126, which areseparated from each other by cut-outs 128, 130, 132. The individualsections 120, 122, 124, 126 of the knife edge 112 engage into thesections 98, 100, 102, 104 of the slit-shaped opening 46, whereby thebridges 106, 108, 110 engage into the cut-outs 128, 130, 132. The outersurface 134 of the cutting roller 40 is provided with circumferentialgrooves 136, 138, 140, which corresponding to the cut-outs 128, 130,134. The outer surface 134 of the cutting roller 40 is provided withcircumferential grooves 136, 138, 140, which correspond to the cut-outs128, 130, 134. The circumferential grooves 136, 138, 140 engage into theguide lands 71 of the circumferential guide elements 68, 70, whereby theguide lands extend circumferentially and transversely to thelongitudinal axis of the cutting roller 42, so that a section of thecircumferential surface 134 of the cutting roller 42 together with theinner surface of the guide lands 71 forms a guide surface, whichsimplifies the guiding of the paper web, in particular during thethreading process.

FIG. 11a ) shows a top view onto the knife 42, comprising the knife edge112 as well as the knife blade 114. The knife 42 is embodied as astamped part.

FIG. 11b ) shows a lateral view of the knife 42. The knife edge 112 isbent relative to the knife blade 114 by an angle α, with α in the rangeof 20°≤α≤60°, preferably α=30°. This ensures that the knife edge 112enters the slit-shaped opening 46 at an optimum angle for cutting thepaper web 24.

In accordance with an aspect of the invention with independent inventivemerit, the outer sections 120, 126 possess a triangular cutting edge,whereby sections 142, 144 or 146, 148 of the cutting edge are embodiedwith an obliquely downward shape in the direction towards the lateraledges 150, 152 or the cut-outs 128, 132.

The invention's embodiment is characterized in that the cutting edges ofthe central sections 122, 124 have flanks 154, 156; 158, 160 that risein the direction of the cut-outs 128, 130, 132, which serves to ensurethat cutting edge sections 162, 164, 166, 168 of the longest possiblelength are formed adjacent to the cut-outs 128, 130, 132, whereby thecutting edge sections interact with the bridges 106, 108, 110 of thepressure roller to cut the paper web in a precise manner, which in turnfacilitates a simple tear-off action.

With respect to the invention's embodiment of the knife edge 112, itshould also be noted that because of the cut-outs 128, 130, 132 thepaper web 24 is only subjected to a type of perforation, instead ofbeing subjected to a complete continuous cut, so that even after thecutting process, the automatic advance due to the tension spring 80 issufficient to transport the paper section 74 to be torn off out of thepaper dispenser, without any risk of a paper jam. After the perforatedpaper section 74 has been dispensed through the opening 76, it maysimply be torn off by a user, which separates the remaining strands inthe paper web 24.

This requires only minimal pulling forces, whereby a further conveyanceof the paper web 24 is prevented by the restoring force of the tensionspring 80.

As a result of the invention's embodiment of firstly the knife edge 112in interaction with the slit-shaped opening 46 with the sections 98,100, 102, 104 as well as the bridges 106, 108, 110, and secondly byfine-tuning the spring tension of the tension spring 80, the invention'sembodiment allows the cutting or rather perforating of paper webs ofdifferent density and strength. In particular, the invention's paperdispenser 10 is to convey paper webs with a density of 2×25 g per mm²,i.e. paper webs that usually can only be used in electrically operatedpaper dispensers. In the prior art, mechanically operated paperdispensers are usually operated using thin paper webs with a density of2×17 g per mm², i.e. single-layer paper.

What is claimed:
 1. A device (26) for separating paper sections (74) from a paper web (24) wound onto a paper roll (22) that provides easy access to the following paper web after the separated paper section has been released, whereby the device (26) comprises at least one cutting roller (40) with a width that corresponds to at least the paper width, with a fixed knife (42) that protrudes from a roller shell and substantially extends across the entire roller width, whereby the knife (42) comprises one knife blade (114) and a series of teeth (120, 122, 124, 126), which are spaced apart along the length of the knife blade (114), whereby the teeth (120, 126) or groups of teeth (122, 124) are separated from each other by cut-outs (128, 130, 132), and whereby the cutting roller (40) is associated with a pressure roller (44), which has a slit-shaped opening (46) and is coupled with the cutting roller (40), characterized in that each of the cut-outs (128, 130, 132) has two cutting edges (162, 164, 166, 168), which extend in parallel to each other and transversely to the longitudinal extent of the knife (42), in that at least one of the cutting edges (162, 164, 166, 168) is a cutting edge of a group of teeth (122, 124) that borders the cut-out (128, 130, 132), and in that the cutting roller (40) comprises along its circumferential surface (134) circumferential grooves (136, 138, 140), each of which corresponds to one of the cut-outs (128, 130, 132).
 2. The device of claim 1, characterized in that the slit-shaped opening (46) of the pressure roller (44) comprises bridges (106, 108, 110) that extend along the circumferential direction, whereby a width and a separation of the bridges (106, 108, 110) correspond to a width and a separation of the cut-outs (128, 130, 132) in the knife, so that during a relative movement between the cutting roller (40) and the pressure roller (44), the bridges (106, 108, 110) engage into the cut-outs (128, 130, 132) of the knife and interact with the adjoining cutting edges (162, 164, 166, 168) in a scissor-like manner.
 3. The device of claim 1, characterized in that the knife (42) comprises a knife edge (112) that protrudes from the cutting roller (40) and forms an angled section.
 4. The device of claim 3, characterized in that the angled section (112) comprises the teeth (120, 126) or groups of teeth (122, 124) and is angled relative to the knife blade (144) along a deflection line at an angle α with 15°≤α≤50°, preferably α=35°.
 5. The device of claim 1, characterized in that the cutting roller (40) comprises two sections (116, 118), which preferably are embodied semi-circularly, and in that the blade (114) of the knife is fixed in position, such as clamped between the semi-circular sections (116, 118).
 6. The device of claim 2, characterized in that the separation of the bridges (106, 108, 110) of the pressure roller (44) corresponds to a width of the group of teeth (122, 124) of the knife edge.
 7. The device of claim 1, characterized in that the groove (136, 138, 140) is embodied with a width and a depth that correspond to the width and the depth of the cut-out (128, 130, 132).
 8. A knife (42) for a device (26) for separating paper sections (74) from a paper web (24) wound onto a paper roll (28), whereby the knife (42) comprises a knife blade (114) with teeth (120, 126) and/or groups of teeth (122, 124), which are arranged spaced apart relative to each other along the length of the knife blade (114), whereby the teeth (120, 126) and/or groups of teeth (122, 124) are separated from each other by cut-outs (128, 130, 132), characterized in that the cut-outs (128, 130, 132) comprise two cutting edges (162, 164, 166, 168) that extend parallel to each other and transversely relative to the longitudinal extent of the knife (42), in that at least one of the cutting edges is a cutting edge (162, 164, 166, 168) of a group of teeth (122, 124) adjoining the cut-out, and in that the cutting edges (162, 164, 166, 168) of the groups of teeth (122, 124) possess edges (154, 156; 158, 160) that rise along the direction towards the cut-out (128, 130, 132).
 9. The knife of claim 8, characterized in that the groups of teeth (120, 122, 124, 126) are angled with respect to the blade (144) along a deflection line by an angle α with 15°≤α≤55°, preferably α=35°.
 10. The knife of claim 8, characterized in that the groups of teeth (120, 122, 124, 126) comprise outer teeth (120, 126), bordering the lateral edge of the blade, as well as at least two inner groups (122, 124) of teeth, whereby the geometry of a cutting edge of the inner groups of teeth is embodied in a W-shape.
 11. The knife of claim 8, characterized in that the cutting edges (162, 164, 166, 168) of the inner groups (122, 124) of teeth that border the cut-outs (130) extend parallel relative to each other.
 12. The knife of claim 8, characterized in that the width and the depth of the groove (136, 138, 140) corresponds to the width and the depth of the cut-out (128, 130, 132).
 13. The knife of claim 8, characterized in that the knife (42) is accommodated in a cutting roller (40), and in that the cutting roller (40) along its circumferential surface (134) possesses circumferential grooves (136, 138, 140), each of which corresponds to one of the cut-outs (128, 130, 132). 